Thyratron firing circuit



Feb. 27, 1962 INVENTOR. WARREN D. PALEY 3,022,732 THYRATRON FIRING ClRCUlT Warren 1). Paley, Great Neck, N.Y., assignor, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Filed Sept. 5, H58, Ser. No. 759,368

7 Claims. (Cl. 102-702) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates generally to an electronic. firing circuit for the primer of a missile explosive train and more specifically is directed to a firing circuit employing an electron tube for the control of the detonating energy.

to an explosive train.

The present invention has the advantage over the previous circuits for similar applications inthat no large amounts of energy can be applied to the primer or detonator except at the desired detonation times.

The electronic firing circuit which comprises the present invention includes a network energized by a sinusoidal power supply which delivers through a thyratron, at the proper time, the desired amount of energy to fire an explosive train of a missile. When the missile is launched the network is energized by the power supply charging two capacitors one of which biases the grid of the thyratron and the other stores energy to be discharged through the cathode of the thyratron to fire the primer after the network has reached a steady-state condition and the charge on the first capacitor has been bled off through a ground due to target influence or; contact. The RC circuit biasing the grid is designed to discharge at a faster rate than the RC circuit storing the energy to detonate the primer.

The present invention'has safety features incorporated therein not found in the prior art. For example energy sufiicient to detonate the primer can only flow through the thyratron after the missile has been in flight a predetermined time and an actual targetcontact has grounded the circuit node controlling the grid bias. If, as a result of fault firing on launching, the node is accidentallygrounded, any charge built up on the capacitor storing the detonation energy will be so small that it will be bled off harmlessly through the primer without causing detonation. Also when the missile fails to make contact with the target in flight and the sinusoidal power supply energizing the firing network has ceased, the RC circuit biasing the thyratron grid will discharge faster than the RC circuit st ring the detonation energyand as soon as the grid potential falls below the critical value the primer detonates thus providing a positive self-destruction circuit for the missile.

Accordingly, an object of the present invention is to provide an electronic firing circuit for a missile explos ve train wherein energy sufficient to detonate the explosive train can only be applied at certain desired times.

Another object is to provide an electronic firing circuit which will detonate a missile explosive trainonly upon target contact or at a predetermined time in flight.

Another object of the invention is to provide a firing circuit wherein the detonation energy delivered to the primer as a result of a fault firing of a missile is insufficient to cause detonation.

Another object is to provide a detonation. circuitry for a missile wherein the missile will destroy itself after a predetermined flight time in the event target acquisition has not occurred.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following de- States atent" tailed description when considered in connection with the accompanying drawings wherein the single figure of the drawing is a wiring diagram of One preferred electronic firingcircuit embodying the present invention.

Referring to the drawings, the alternating current supply lines 16 and 11 are connected to the primary winding 12 of a transformer 13 which is also equipped with a pair of secondary windings 14 and 15. A pair of terminals 10 and 11 and a switch means (not shown) interconnects the terminals 16 and 17 prior to the time the missile (not shown) is launched and thus prevents current from flowing through the transformer 13 until the missile is launched. Upon launching of the missile the above mentioned switch means is opened and sinusoidal power supply from the terminals 10 and 11 energizes the firing circuit as noted below. 7 i

The secondary winding 14 has one end terminal 19 connected to ground and the other terminal 20 is connected through a pair of leads 21 and 22 to the RC circuit for biasing the grid or control electrode 24 of the thyratron 23 and the RC circuit storing the energy to fire the primer 25. V

The circuit for biasing the grid 24 comprises a pair of diodes or half wave rectifiers 26 and 27 connected in series to the lead 21 so as to charge the capacitor 29 during the negative half cycle of the alternating current impressed thereon whereby the plate of the capacitor 29 which is connected through the lead 36) and resistor 31 to the grid 24 is negative. Hence the negative charge on the grid 24 blocks the conduction of the thyratron 23 as will appear hereinafter.

The negativecharge on the plate of the capacitor 29 and the grid 24 can be discharged to ground either rapily through a terminal 32 which is grounded either by a switch means (not shown) upon target influence or contact with the missile or upon failure of the power supply through a resistor 33 connected to the lead 30.

The RC circuit for storing the detonation energy comprises a pair of diodes or half wave rectifiers 34 and 35 connected in series to the lead 22 whereby the capacitor 36 is charged during the negative half cycle of the alternating current impressed thereon in the same manner as the capacitor 29 is charged. The plate of the capacitor 36 is connected by a lead 37 to the circuit of the cathode 39 of the thyratron 23. A resistor 40 interconnecting the diode 35 and the capacitor 36 has a higher electrical value than the resistor 33 whereby the capacitor 36 discharges at a much slower rate than the capacitor 29 when the power supply fails for reasons hereinafter described.

A heating circuit for the cathode 39 includes a pair of end terminals 41 and 42 from the secondary winding 15 with an impedance coil 43 in the lead from the terminal 42.

In operation, the switch means interconnecting the terminals 16 and 17 is opened upon launching of the missile and the firing circuit is energized by the sinusoidal power supply 10-41. While the missile is in flight the capacitors 29 and 36 are given a negative charge on their plates through the secondary winding 14 and their respective diodes. As the missile is in flight and prior to the normal time for target acquisition the network reaches a steadystate condition wherein the capacitors 29 and 36 are fully charged,'the cathode 39 has a negative charge and the control grid 24 has a negative bias thereon.

Upon target contact the plate of the capacitor 29 and the negative bias on the grid 24 are discharged to ground through terminal 32. The grid 24 and the plate 45 are then at a positive potential with respect to the cathode 39 allowing the capacitor 36 to discharge through the conducting tube 23 and detonate the primer 25.

The safety features incorporated in the circuit are:

(1) Suflicient'energy to fire the primer 25 cannot be applied prior to the desired detonation time since current can only flow through the primer 25 after the terminal 32 has been grounded due to target acquisition;

(2) If, as a result of a fault firing on launching, the terminal 32 is accidentally grounded, any charge building up on the capacitor 36 will be bled off harmlessly through the primer 25. Under these circumstances the tube 23 circuit can be arranged to fire at a low plate-cathode potential thereby delivering a demonstrably small amount of detonating energy to the primer;

(3) In flight, self-destruction upon failure of target acquisition and power supply is obtained as follows: the RC circuit biasing the grid 24 will discharge through the resistor 33 much faster than the RC circuit storing the detonation energy will discharge through the resistor 40. As soon as the grid 24 potential fallslbelow the critical value the primer is detonated, setting OK the explosive train; and

(4) In the event the missile has a combination electromechanical arming device the electronic arming can be arranged to either precede or follow the mechanical arming in accordance with the safety requirements.

As can readily be seen the presentinvention has many advantages over previous circuits for similar applications in that no large amounts of energy can be applied. to the primer 25 except at the desired detonation times.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. An electronic firing circuit comprising an alternating current source, first and second capacitors, a normally non-conducting electron tube having one of its main elec trodes connected to, said first capacitor and havingv a control electrode upon which initiation of its conduction is dependentconnected to said second capacitor, rectifying means deriving energy from said source for supply to said first and second capacitors and limiting said energy supplied to said capacitors to half. cycles of the same given polarity of the voltage of said source, an explosive train primer connected to the other main electrode of said electron tube andmeans. for. grounding said second capacitor and control electrode for permitting said tubeto conduct and fire said primer.

2. Anelectronic firing circuit comprising a. sinusoidal power supply, a pair of capacitors, rectifying means deriving energy from said power supply for supply to said capacitors whereby said supplied energy is limited to half cycles of the same givenpolarity of. the voltage of said power supply, a normally non-conducting electron tube having one of its main electrodes connected to one of said capacitors and having a control electrode upon which initiation of its conduction is, dependent connected tothe other of said capacitors, an explosive means associated with the other main electrode of said electron tube and means for controlling the potential of said control electrode whereby said tube conducts to fire said explosive means at a predetermined time.

3. An electronic firing circuit for a missile explosive train comprising in combination, a sinusoidal power supply, a normally nonconducting electron tube, first and second RC circuits connecting said power supply with the grid and cathode respectively of said tube, means connecting a primer in said explosive train with the anode of said tube and means for discharging said first RC circuit biasing said grid whereby the energy stored in said second RC circuit is conducted through said tube to fire said primer.

4. An electronic firing circuit as defined in claim 3 in which a switch means associated with said power supply is provided to control energizing of said circuit prior to launching of said missile.

5. An electronic firing circuit as defined in claim 3 in which said first and second RC circuits comprise a pair of capacitors, rectifying means associated with each of said capacitors and deriving energy from said power supply whereby the voltage applied to said capacitors is limited to the negative half cycle; of the voltage of said power supply.

' 6 An electronic firing circuit as defined in claim 3 in which discharge means are provided for the first and secondRC circuits upon failure. of said power supply, said means including a first resistor connecting saidfirst-RC circuit to ground and a second resistor having a higher electrical value than said first resistor connecting said second RC circuit to ground whereby said first RC circuit discharges at a faster rate than said second RC circuit.

7. An electronic firing circuit for delivering, at the proper time, the desired amount of energy to fire an explosive train of a missile comprising; a network energized by a sinusoidal power supply, said network including a transformer having its primary winding connected to said power supply, a pair of capacitors associated with a secondary Winding of said transformer, rectifying means interconnecting said secondary winding and each of said capacitors and limiting energy supplied to said capacitors to half cycles of the same given polarity of the voltage of said power supply, a normally non-conducting electron tube associated with said capacitors, whereby one of said capacitors controls the grid bias of said tube and the other of'said capacitors stores energy to discharge through said tube, a primer of said explosive train operably connected to said tube and means for discharging said one capacitor and grid whereby said stored energy conducts through said tube to fire said primer.

References Cited in the file of this patent UNITED STATES PATENTS 2,873,679 Gibson Feb. 17, 1959 

